Photographic apparatus



Patented Sept. 3,, 1935;

UNITED STATES AUTOMATIC DIAPHRAGM fidiin Riszdorfer, Budapest, Hungary Application July 18, 1932, Serial No. 623,216 In Hungary July 18, 1931 3 Claims.

The invention relates to apparatus adapted to vary the area of the light aperture of photographic cameras in which apparatus the screening members by means of which the light aperture-is defined are actuated by the current of a photo-cell. Openings are provided in the screening members and the mutual arrangement of the screening members is such that the openings provided overlap each other in part or (in case of full opening) entirely, so as to allow the light sensitive emulsion to become exposed to light entering through the aperture thus formed.

An arrangement embodying my invention is shown, byway of example, on the accompanying drawing, on which:

' Fig. 1 is a side view of the apparatus for varying the light aperture, parts of the same being in section;

Fig. -2 is a plan of the said apparatus;

v Fig. 3- illustrates an apparatus for varyin the area of light apertures of photographic cameras embodying the invention.

In these Figures 11 and 12 are two permanent magnets located one above the other, mutually co-axial coils l3 and I4 being provided to oscillate respectively, between the poles of each 'of the magnets referred to. The coils are fitted i. e. connected into the circuit of the photo-elec tric cell in such a manner as to make-the deflections to which they will be subject mutually opposite in each case. Screen elements I5 and I6 located in mutually parallel positions on which elements square-shaped openings i9 and 20, respectively, are provided, are fixed on the oscillating coils l3 and These openings are arranged so as to make .the amount of "their mutual overlap vary in proportion to the deflection the screening elements. When no current flows from the photocell, that is to say, when no currents flows through the spools l3 and N; the two diaphragm elements I5 and I6 are inja posiizion in which each diaphragm element correctly registersor covers the other diaphragm element and the diaphragm openings l9 and 20 register one with the other, and hence, the diaphragm is completely open. The strongerthe current passing through the spools l3 and II, the further the elements l5 and IE will swing ,relative to each other in the directions of the arrows, (Fig. 2), and the smaller will become the opening of the diaphragm. When no light hits the cell, the current through the spools l3 and II is interrupted and they become 'deenergized and the shutters regain their normal positions, completely covering each other. The backward movement of the diaphragms into what may be regarded as the zero or initial position may be efiected in any appropriate manner, as by employing a spring, exerting force on the spools i3 and M to cause a reverse of their movement counter to that into 5 which they are moved when energized.

In the example shown the two screening elements are located between the two halves i1 and l8 of the object lens of the camera. In case square-shaped openings are employed, these open- '10 ings are preferably arranged so as to make, in the case of both openings, the two corner points 2! and 23 situated opposite to each other, of each opening .to be located at the same distance from the axis .of oscillation and to form at the same 15 time points of a circular arc passing through the optical axis of the object lens thus causing the two other corner points 22 and 24 to be located along one and the same radius. The reason why this arrangement is particularly favourable is 20 that with this arrangement it will be two corner points which, during the movement of opening will come into mutual contact first, and that. the shape subsequently formed during the further course of the movement ofopening will be a 25 symmetrical quadrangular shape, the centre of which will be situated in the optical axis of the lens system. W

I The screens possess parts 28 extending beyond the co-axial shafts 25 which parts are preferablrao made so as to .balance those parts of the screens as have been cut out to form the openings. One of the counterweights is a pointer permitting the. magnitude of the light aperture at any time to be read oiT scale 29. In the case of this arrangement all the resistance which in addition to the magnetic-resistances has to be overcome by the current of the photo-cell consists in the pin frictions which in instruments of this kind are of. very small magnitude. The openings may also be of other than square shape. Notably, the sides of the openings may also be curved instead of straight-lined, thus enabling the centre of the light aperture to be permanently kept'in'the optical axis. It is immaterial from the point of view'of the invention whether the diaphragm is placed in front of the object lens, behind the object lens or between the individual lenses forming the object lens. Of course, the screening elements may also be more than two in number.

What I claim is: a

1. In a photographic camera, the combination of. diaphragms, said diaphragms having openings through both of which light is projected when in operation, means for oscillatively mounting the Patented Sept. 3, 1935 v I p UNITED STATES PATENT OFFICE PHOTOGRAPHIC APPARATUS than Riszdorfer, Budapest, Hungary Application September 12, 1932, Serial No. 632,816 In Hungary September 12, 1931 6 Claims. (Cl. 88-23) I have filed an application for patent upon ,this corresponding degree of sensitivity of emulsion apparatus in Hungary on September 12, 1931. required etc.

The invention relates to a device for measur- The current of the photo-cell may be controlled ing the intensity of illumination, of the type in by means of resistances inserted into the circuit which a photo-electric celi is employed. which resistances are capable of being varied in 5 In taking photographs, the quantity of light accordance with the magnitude of the various ensuring correct exposure is in the types of camfactors. It is also possible however, to control it eras generally used determined by two factors, by means of variable diaphragms or by means viz. the magnitude of the diaphragm opening and of a combination of diaphragms and resistances;

the shutter speed. These two factors are in muat the same time the exact desired magnitude of 10 tual dependence, and if, with a given intensity the picture angle of the device for measuring the of illumination the value of one of them is asintensity of the illumination can be assured by sumed, this already determines the most advanapproaching the photo-cell to the opening for the tageous value of the other factor. The intensity admission of light of the device for measuring the is of illumination can be determined with a high intensity of illumination, or removing the phodegree of accuracy by means of photometers comto-cell to a greater distance from the said openprising photo-cells. If, after obtaining the figure ing.

of the intensity of illumination, one of the two Embodiments of my invention shown by way factors referred to, e. g. the magnitude of the of example, are illustrated in detail on the andiaphragm opening is chosen at a suitable figure, nexed drawing, in which 20 it becomes possible to calculate the other factor, Fig. 1 illustrates the device for measuring the.

viz. in the case of my example, the corresponding intensity of illumination, in front elevation, and

shutter speed. Correct exposure is however, inpart section, whilst fiuenced, in addition to shutter speed and magni- Fig. 2 is a perspective view of a second form of tude of diaphragm opening, by other factors as the apparatus with the indicating means arwell, notably by the sensitivity, usually expressed ranged in the interior of the casing.

in Scheiner degrees, of the emulsion employed, Fig. 3 is a perspective view of the device shown the nature of the colour filters employed, and in Fig. 2 with portions in section. the picture angle of the picture to be taken. Casing I contains the movable inner casing 2,

3d The device for measuring the intensity of illuat the end of which the photo-electric cell 3 is mination according to the invention enables all arranged. Light enters through the opening 4 these factors to be'taken into account by allowand falls on the photo-electric cell 3, which in ing these various factors to influence the circuit my example is a photo-voltaic cuprous oxide cell,

of the photo-cell in an additive manner. After and induces a current in the circuit 5 of the cell.

3& having selected on the photographic camera the The current flows in the current indicating inmagnitude of the diaphragm opening, the sensistrument 6 through the coil 8 situated between tivity of the emulsion, the picture angle of the the magnet-poles of the horse-shoe-shaped percamera etc. these already determine the most manent magnet I and deflects the latter together favourable shutter speed also. If therefore the with the needle 9 in front of the scale I!) the to circuit of the photo-cell on the device for measdivisions of which represent shutter speeds. The uring the intensity of illumination is permitted quantity of light falling on the cell is influenced to be influenced in proportion to the various by means of the diaphragm H which latter is factors chosen on the photographic camera, the adjusted by means of the diaphragm setting i2. current intensity of the photo-cell circuit will The needle l3 fixed on the diaphragm setting be proportionate to the best shutter speed. Inmoves in front of the diaphragm scale M. The 45 stead of reading-oil current intensities from the contact lever of the resistance It, which controls measuring instrument indicating the current inthe variable resistance I! connected into the cirtensity of the photo-cell, it is possible to immecuit of the cell moves in front of the scale part diately read off the corresponding shutter speeds l5, the divisions of which represent the degrees themselves. of sensitivity of the emulsion. The picture angle Inthe same way it is possible to determine for can be varied by fixing the inner casing 2, by the shutter speed chosen beforehand, the corremeans of screw 19, in various positions in front sponding magnitude of the diaphragm opening, of the scale part 18 which latter registers the or, for instance, to determine, for a given shutter picture angle. The magnet can also be arranged .5 speed and magnitude of diaphragm opening, the around the casing I. In this case, the instrument for measuring current intensity called in what follows, in short, the ammeter, is also placed inside the casing. The needle 2| of the ammeter moves in front of the scale 22. The scale is engraved on the glass plate 23. In order to enable the scale to be observed, a circular opening 24 is provided on the photo-cell, the cone for the protection of the operator's eye being placed in front of this opening.

When making use of the device for the measurement of the intensity of illumination the picture angle of the cell is adjusted on scale I 8 so as to correspond to the picture angle of the photographic camera. Diaphragm H is adjusted so as to correspond to the diaphragm opening of the camera, whilst the degree of sensitivity of the emulsion is taken into account by adjusting on scale |5,-the divisions of which represent degrees of sensitivity of emulsion, the contact lever 16 moving over the variable resistance l1.. Following'this the device for measuring the intensity of illumination is aimed at the object to be photographed. A current the intensity of which corresponds to the intensity of illumination of this object, but is, also influenced by diaphragm H and by resistance II, will flow in the circuit of the photo-cell. The cell current influenced in accordance with the various factors will deflect the needle 9, which latter will indicate on scale ill the most favourable shutter speed corresponding to the intensity of illumination of the object, to the chosen diaphragm opening of the camera and to the degree of sensitivity of the emulsion employed. In the case of the arrangement shown in dotted lines the method of operation is the same.

The substance of the invention consists in influencing the circuit of the cell in accordance with various factors determining correct exposure, as shutter speed, magnitude of diaphragm opening, degree of sensitivity of emulsion etc. Accordingly it is possible to employ, instead of .the diaphragm ll shown in the example described, a second resistance connected into the circuit of the cell, such resistance being varied in proportion to the magnitude of the diaphragm opening of the camera. Similarly the chosen shutter speed can be adjusted by means of a resistance and in this case the needle of the ammeter will instead of indicating shutter speed as in the example described, indicate the corresponding magnitude of diaphragm opening. In

case it is desired to take into account, in addition to the above, other factors determining correct exposure as well, all that has to be done is to insert further resistances, capable of being suitably varied, into the circuit of the photo-cell. What I claim is:

1. In an exposure meter for photographic purposes, a tubular casing having an opening at one end for the admission of light and a sight hole at its other end, a diaphragm controlling the first opening, a transparent scale-bearing member in the casing visible through said sight opening, a

pointer pivoted in the casing to traverse said scale, an electro-magnetic device in the casing carrying said pointer to move the pointer over the scale, a photo-electric cell in the path of the light from the diaphragm opening to the sight opening apertured to allow light to pass' therethrough to the sight opening, and series connections between said cell and electro-magnetic means.

2. In an exposure meter for photographic purposes, a tubular casing having an opening at one end for the admission of light and a sight hole at its'other end, a diaphragm controlling the first opening, a transparent scale-bearing member in the casing visible through said sight opening, a pointer pivoted in the casing to traverse said scale, an electro-magnetic device in the casing carrying said pointer to move the pointer over the scale, a photo-electric cell in the path of the light from the diaphragm opening to the sight opening apertured to allow light to pass therethrough to the sight opening, and series connections between said cell and electro-mag'netic means, said scale being graduated to indicate one of the camera functions including the two functions of shutter speed and camera diaphragm opening and the cell having its light sensitive elements wholly within the casing.

3. In an exposure meter for photographic purposes, a tubular casing having an opening at one end for the admission of light and a sight hole at its other end, a diaphragm controlling the first opening, a transparent scale-bearing member in the casing visible through said sight opening, a pointer pivoted in the casing to traverse said scale, an electro-magnetic device in the casing carrying said pointer to move the pointer over the scale, a photo electric cell in the path of the light from the diaphragm opening to the" sight opening apertured to allow light to pass therethrough to the sight opening, and series connections between said cell and electro-magnetic means said casing includinga pair of telescopic tubes and means to adjust the telescopic relation of said tubes, the

diaphragm being at the outer end of one'tube and the sight opening at the outer end of the other tube.

4. In an exposure meter for photographic purposes, a tubular casing having an opening at one end for the admission of light and a sight hole at its-other end, a diaphragm controlling the first opening, a transparent scale-bearing member in the casing visible through said sight opening, a-pointer pivoted in the casing to traverse said scale, an electro-magnetic device in the casing carrying said pointer to move the pointer over the scale, a photo-electric cell in the path of the light from the diaphragm opening to the sight opening apertured to allow light to pass therethrough to the sight opening, and series connections between said cell and electro-magnetic means, said electro-magnetic means including an arcuate permanent magnet concentric with the optical axis of the casing to present free passage of light from the diaphragm to the sight opening.

5. In an exposure meter for photographic pur poses, a tubular casing having an opening at one end for the admission of light and a sight hole at its other end, a diaphragm controlling the first opening, a transparent scale-bearing member in the casing visible through said sight opening, a pointer pivoted in the casing to traverse said scale, an electro-magnetic device in the casing carrying said pointerv to move the pointer over the scale, a photo-electric cell in the path of the light from the diaphragm opening to the sight opening apertured to allow light to pass therethrough to the sight opening, series connections between said cell and electro-magnetic means, and a regulatable resistance in said series connections. v v

6. In an exposure meter for photographic purposes, a tubular casing having an opening atone endfor the admission of light and a sight hole at its other end, a diaphragm controlling the first opening, a transparent scale-bearing member in the casing visible through said sight opening, a

- pointer pivoted in the casing to traverse said scale, an electro-magnetic device in the casing carrying said pointer to move the pointer over the scale, a. photo-electric cell in the path of the light from the diaphragm opening to the sight opening apertured to allow light to pass therethrough to the sight opening, series connections 6136: RISZDORFER. 

